Typewriting machine



Aug. 20, 1940. B DOWD 2,211,967

TYPEWRITING MACHINE Filed Oct. l, 1938 Patented Aug. 20, 1940 UNITED STATES PATENT OFFICE TYPEWRITING MACHINE Bernard Joseph Dowd, West Hartford, Conn'., assignor to Royal Typewriter Company, Inc., New York, N. Y., a corporation of New York Application October 1,

6 Claims.

This invention relates to typewriting machines, and more particularly to typewriter keys. Keys embodying the invention may, however, be applied to nger-operated members of other machines, such as adding machines, computing machines and the like.

One type of key in general use includes a cup orbase part supporting a disk of cardboard or the like displaying a character and being covered with a disk or ordinary glass positioned Ato protect the character and to be engaged by the operators fingers. An objection to covering disks formed of glass is that the glass is susceptible to breakage both during assembly of the key and in use. Furthermore, as a material, glass is practically inflexible and is not well adapted for molding or cutting in small units to form disks of special design.

As substitutes for the usual glass disks and in attempts to overcome the disadvantages inherent A in glass disks, key cover disks also have been made of Celluloid and other molded substances, but such disks have been found to have other disadvantages. One principal disadvantage of molded materials heretofore used has been their susceptibility to becoming scratched. whereby their transparency has been impaired, not only rendering it more dimcult to see the character, but giving the entire keyboard a dingy appearance.

An object of the invention is to provide a typewriter key character-cover disk having improved properties and in which the disadvantages of key cover disks heretofore known are eliminated.

In accordance'with one feature of the invention, a typewriter key is provided with a cover disk of molded plastic material possessing advantages not heretofore known or appreciated as making it especially eiilcient and serviceable when used in typewriter keys. The material found most satisfactory is methyl methacrylate plastic, preferably such material known by the proprietary name, Lucite. This materialv is crystal clear, so clear that it is possible to read news print through a thick block of it. It is considerably more clear and transparent than otherr plastics.

It is only about half as heavy as common glass, is somewhat flexible, non-shattering, strong and durable, and is not readily scratched. Sunlight does not affect its clearness or color; it is unaffected by most chemicals, and is substantially non-hygroscopic. Itis superior to Celluloid and cellulose acetate materials in that its surfacev is harder, being thereby less easily scratched, it is 193s, serial No. 232,863

(Cl. isi-1oz) more transparent, it will not discolor, and it is substantially non-inflammable. A surprising propertyl rendering it particularly serviceable for vcover disks for typewriter keys is that the material is polishable by the normal touch of the I operators ngers during typing, so as to have its transparency and crystal clearness thereby maintained substantially unimpaired.

Another object is to provide a typewriter key assembly of novel and improvedconstruction.

A further object is to provide a typewriter key assembly of novel construction adapting it especially for the incorporation therein of a transparent cover disk of somewhat flexible material.' Other objects will become apparent from a reading of the following description, the appended claims and the accompanying drawing in which:

Figure 1 is a vertical sectional'view of one embodiment of the invention, the section being taken on the line I-I of Figure 2;

Figure 2 is a bottom plan view looking in the direction of the arrows 2--2 in Figure l;

Figure 3 is a view similar to Figure l but showing a modiilcation; f

Figure 4 is a similar view showing another modification;

Figure 5 is a similar view of a further cation; and

Figure 6 is a top plan view of the assembly shown in Figures 1 and 2 and drawn on a smaller scale.

Among the several constructional forms of the invention shown for the purposes of illustration, Figures 1 and 2 show a portion only of a key lever A, which may be of usual form, and which serves to mount a key assembly generally designated B. The key assembly includes a cup C having a bottom or base I and an annular side wall 2. A washer 3 disposed within the cup is provided with a slot l registering with a slot 5 in the base of the cup, the two slots receiving a key lever shank 6 which is peened out as at 1 to secure the key lever, cup, and washer in assembled relation. The washer is formed with opposed raised flanges 8 serving a purpose to be described.

A disk 9 `of cardboard or the like displaying a character I Il on its upper face is positioned within the cup so as to rest upon theflanges 8. A transparent disk Ii, preferably and in accordance with one feature of the invention'being as described and having theproperties and characteristics referred to above, is positioned over the character disk I0 and protrudes slightly above the cupside wall 2.

A key cap I2 is provided for holding the trans- 55 modiparent disk down against the character disk l and the latter against the washer flanges l. In the form shown in Figures 1 and 2 the key cap includes a' rim I3 adapted to nt the cup wall 2 and an inwardly turned flange I 4 overlying the marginal portion of the transparent disk Il. In order that the key will present a neat appearance vand a smooth surface for the touch of the operators iingers, the upper marginal part of the disk Ais recessed as at I5 in such manner as to receive the cap flange Il so that the top oi the flange will be ilush with the top surface of the disk l I.

The parts may be held in assembled relation by ears I8 formedintegrally with the cap l2 and turned under the bottom of the cup. The transparent disk Il is of uniform thickness. having a concave top surface and a convex bottom suriacel An additional advantage of the material described above is that it can readily be molded in forms such as that shown in Figure 1. The washer anges 8-8 serve to support the character disk 9 and the transparent disk Il held down by the'cap I2, and prevent the parts from becoming'loose and rattling after long use. Preferably the ange Il is slightly yieldable so that the partsmay be heldunder a continued compressive force after the ears I8 have been turned under the cup. Since the transparent disk Il itself is somewhat flexible, there is no danger of breaking it when placing the parts under compression during assembly. Thus. the characteristics of the disk Il and the yieldability of the flange I4 contribute to the making of a firm, permanently tight assembly.

In the embodiment shown in Figure 3 the key lever A, cup CB and washer 3 are the same as the corresponding parts in the Figure 1 embodiment, with the exception that the annular side wall 2* of the cup shown in Figure 3 is relatively more shallow than the wa1l2 of the cup shown in Figure 1. The transparent disk I'l diiers from the disk II in the Figure 1 form in that its bottom fac'e is flat instead of convex, the character disk 9l also being flat. 'I'he peripheral edge portion of the disk Il* is beveled upwardly and inwardly as at I5n instead of being angularly recessed, and extends over the annular wall 2'l of the cup. In the Figure 3 modiilcation, a key cap i2l having a rim I3l ltting the cup is provided with an inwardly turned somewhat flexible flange lll, the extreme inner edge of which is tapered on' in thickness so that the bottom of the tapered edge portion will lie snugly against the beveled periphery I5al of the disk Il, and the top oi' the flange inner edge will be substantially ush with the top of the disk II. Ears I6* on the cap i2* bent in under the bottom il of the cup, hold the parts together rmly. 'Ihe key assembly Bl thus provided possesses the particular advantage that it is not necessary to maintain extremely precise or close tolerances in the dimensions of the transparent disk and the key cap in order to provide a neat, permanently strong assembly. Thus, if the diameter of the inner edge of the flange Il isslightly greater than the diameter of the upper peripheral edge of the transparent disk I I, the tapered portion of the ilange i4* still will lie snugly against the beveled edge l5l of the disk, and in the assembled key, any small discrepancy in dimensions of the component parts will not be discernible.

In the form shown in Figure 4 the construction and arrangement of the parts is the same as in the Figure 3 embodiment with the exception that in the Figure 4 form, the transparent disk Il, provided with a beveled peripheral edge Il, is convex on its bottom race, and the character disk Ibis curved or dished accordingly. Otherwise the parts oi the Figure 3 assembly B and the Figure 4 assembly Bb are similar and are designated by corresponding reference characv ters.

The assembly 13, shown in Figure 5, is generally similar to the assembly shown in Figure 4, and corresponding parts are designated by similar reference characters in the two figures. The Figure 5 form diiiers from the Figure 4 form in that the transparent disk |I, shown in Figure 5, tits within the annular cup wall 2 instead of over the cup'wall as in Figure 4, and the upper portion only of the periphery o1' the disk Il is beveled at lli?, the lower portion being substantially perpendicular to the cup bottom I c and being iltted within and centered by the cup wall 2.

In all three assemblies B, Bb and Bc shown in Figures 3, 4 and 5, respectively, the yieldability of the key cap flanges and the non-shattering property of the material forming the transparent disks makes it possible to' press the parts rmly together in assembling without danger of breaking or chipping the transparent disks. However, transparent cover disks formed of the material described and possessing the characteristics and properties speciiied above may be embodied in various key assembly constructions. Some other forms of key assemblies which may include transparent disks of material as described herein are disclosed and claimed in the copending application of William O. Michelsen, Serial Number 232,888, filed October 1, 1938. 'I'he forms disclosed are preferred, but changes may be made in the construction and arrangement of the parts without departing from the invention as` deilned in the claims.

I claim:

1. In a key of the character described, a key cup equipped to display a character; a transparent cover disk supported by the cup and through which the `character is viewable, said disk having a beveled peripheral edge portion; and a disk-retaining key cap ring including a rim iltted to said cup and an inwardly turned ilange contacting the upper inner portion only of the beveled peripheral edge portion oi said disk.

2. In a key of the character described, a key cup equipped to display a character; a transparent cover disk supported by the cup and through which the character is viewable, said disk having a beveled peripheral 'edge portion; and a disk-retaining key cap ring including a rim fitted 'to said cup and an inwardly turned ilange, the extreme inner edge portion oi said flange being tapered oi in thickness with the bottom of the tapered portion contacting the upper inner portion only of the beveled peripheral edge portion of said disk, and the top of said ilange inner edge portion lying substantially ilush with the marginal portion of said disk.

3. In a key of the character described, a key cup equipped to display a character; a transparent cover disk supported by ,the cup and through which the character is viewable. said disk having a beveled peripheral edge portion; and a disk-retaining key cap ring including a rim fitted to said cup and an inwardly turned ilange contacting the upper inner portion only oi' the beveled peripheral edge portion of said disk, the periphery-of said disk being disposed above the periphery of the cup and concentrically within the cap rim.

4. In a key of the character described, a key cup equipped to display a character; a transparent cover disk supported by the cup and through which the character is viewable, said disk having a beveled peripheral edge portion; and a disk-retaining key cap vring including a rim fltted to said cup and an inwardly turned slightly yieldable ange contacting the upper inner portion only of the beveled peripheral edge portion of said disk.

5. In a key of the character described, a key cup equipped to display a character; a transparent cover disksupported by the cup and through which the character is viewable, the lower part of the peripheral edge oi' the disk being substantially perpendicular to the bottom of the cup andthe upper part of said peripheral edge being beveled upwardly-inwardly; and a disk-retaining key cap ring including a rim iitted to said cup and an inwardly turned flange contacting the upper inner portion only of said beveled edge part, said lower edge part of the disk being disposed within the cup and said beveled upper edge part extending above said cup, said cap flange being disposed above and out of contact with the uppermost part of the cup.

6. In a key of the character described, a key cup equipped to display a character; a transparent cover disk supported by the cup and through which the character is viewable, said disk having a beveled peripheral edge portion; and a disk-'retaining key cap ring including a rim iitted to said cup and an inwardly turned ange contacting the upper inner portion only of the beveled peripheral edge portion of said disk, the extreme inner edge portion of said flange being tapered oil in thickness, the top of said flange inner edge portion lying substantially ilush with the marginal portion of said disk, and the bottom of said iiange inner edge portion substantially conforming to and lying against the beveled peripheral edge portion of said cover disk.

BERNARD JOSEPH DOWD. 

